Keyboard and switching mechanism for electrical musical instruments



Aug. 5, 1958 L. HAMMOND 2,845,831

KEYBOARD AND SWITCHING MECHANISM FOR ELECTRICAL MUSICAL INSTRUMENTS Original Filed June 23, 1950 5 Sheets-Sheet 1 m P3 1 T L \lll'llllj IR @0224 052M202 8122.25 .Ezw mm H0232 N622 1,22 E me K fawn/n4 wa/m/mon WP W Aug. 5, 1958 L. HAMMOND. 2,845,831

KEYBOARD AND SWITCHING MECHANISM FOR ELECTRICAL MUSICAL INSTRUMENTS Original Filed June 23, 1950 5 Sheets-Sheet 2 Aug. 5, 1958 L. HAMMOND KEYBOARD AND SWITCHING MECHANISM FOR ELECTRICAL MUSICAL INSTRUMENTS 5 Sheets-Sheet 3 Original Filed June 25, 1950 Aug. 5, 1958 L. HAMMOND 2,845,831

KEYBOARD AND SWITCHING MECHANISM FOR ELECTRICAL MUSICAL. INSTRUMENTS Original Filed June 23, 1950 5 Sheets-Sheet 4 Aug. 5, 1958 HAMMOND 2,845,831

- KEYBOARD AND SWITCHING MECHANISM FOR ELECTRICAL MUSICAL INSTRUMENTS Original Filed June 23, 1950 5 Sheets-Sheet 5 United States Patent KEYBOARD AND SWITCHING MECHANISM FOR ELECTRICAL MUSICAL INSTRUMENTS Laurens Hammond, Chicago Ill., assignor to Hammond Organ Company, a corporation of Delaware Original application June 23, 1950, Serial No. 169,902. Divided and this application February 5, 1953, Serial No. 335,357

4 Claims. (Cl. 84-423) This application is a division of my copending application Serial No. 169,902, filed June 23, 1950, which was abandoned after this application was filed.

This invention relates generally to musical instruments having electrical circuits for controlling the production of musical tones. The invention is particularly applicable to musical instruments which have generating systems for producing electrical tone signals.

This invention provides a musical chord selecting echanism having a plurality of control elements manually operable individually to control the production of complete accompaniment chords. The chord selecting mechanism of this invention may be employed in cooperation with a plurality of musical tone sources to provide a complete accompaniment section of a musical instrument. Operation of any one of the control elements of the chord selecting mechanism is eflective simultaneously to cause the sounding of a plurality of harmonically related tones by the tone sources.

For example, the chord selecting mechanism of this invention may form a cooperative part of the complete electrical musical instrument described in the copending U. S. patent application of John M. Hanert, Serial No. 169,891, filed June 23, 1950, which on July 21, 1953, matured into Patent No. 2,645,968. That application describes electrical musical instruments having accompaniment tone signal generating systems including pluralities of electronic oscillators.

One of the embodiments described in the Hanert patent includes six vacuum tube oscillators for producing accompaniment chord electrical tone signals and for determining the pitch of low pitched bass tone signals produced by the instrument. In order to cover a full octave of twelve tones, each of the six oscillators is tunable to a pair of adjacent semitone pitches. For this purpose each of the oscillators has a switch for changing the pitch of the oscillator by an interval of a single semitone.

Each of the oscillators also has a keying switch to control the effectiveness of the oscillator to transmit a tone signal to a common output system.

In this particular embodiment described in the Hanert patent, one of the six chord oscillators is tuned to the pitch of the root or the selected chord and another oscillator is tuned to the fifth of the chord. These two oscillators are connected respectively to root and fifth output conductors which supply tone signals to a frequency dividing system for producing a low frequency bass electrical tone signal having either a root or a fifth pitch in a lower octave. Each of the six chord oscillators has a pair of switches for selectively connecting the oscillator with the root and the fifth output conductors respectively.

Thus an instrument such as that disclosed in the Hanert patent has a plurality of electrical switches which must be operated in various combinations in order to produce a plurality of harmonically related chord tones simultaneously. This invention provides a button keyboard and a switching mechanism for switching a .pluralice ity of the electrical circuits of a musical instrument simultaneously, in selected combinations, by the operation of predetermined individual control buttons.

The general object of this invention is to provide apparatus whereby a plurality of musical tones comprising a harmonic chord may be simultaneously sounded by the operation of a single control element.

A further object is to provide a mechanism for selecting harmonic accompaniment chords in one of several musical keys and one of several harmonic variations.

A further object is to provide a button keyboard and switch mechanism for switching the electrical control circuits of a musical instrument, selectively to produce harmonic accompaniment chord tones.

A further object is to provide a button keyboard .and switch mechanism to control, by the operation of a selected button, the furnishing of electrical tone signals from a plurality of sources to an output or utilization system for producing a selected musical chord.

A further object is to provide a switch mechanism, operable by an accordion type button keyboard, for concurrently actuating desired combinations of a plurality of switches.

.A further object is to provide such a switch mechanism for operating any desired combination of a plurality of switches in a definite sequence.

A further object is -to provide such a switch mechanism consisting almost entirely of parts stamped from sheet metal.

A further object is to provide a switch mechanism, operable by an accordion type button keyboard, for operating selected combinations of a plurality of parallel switch actuating levers by means of a plurality of perpendicular button levers.

A further object is to provide such a switch mechanism including thin sheet metal button levers having a plurality of downwardly extending projections for operating selected combinations of a plurality of sheet metal switch actuating levers.

A further object is to provide such a switch mechanism including a plurality of thin sheet metal button levers supported in a plurality of bins by stationary plates, in order to minimize buckling of the levers.

A further object is to provide such a switch mechanism, including a plurality of thin sheet metal key levers spaced apart by indentations or dimples stamped in the levers, in order to prevent adjacent levers from adhering to one another.

A further object is to provide a switch mechanism, operable by .an accordion type button keyboard, having a plurality of long flexible contact springs operable by individual switch actuating levers which are operated in selected combinations by individual control levers perpendicular to the switch levers, the switch levers being positioned at different distances from the pivot of the control levers.

A further object is to provide a chord selecting switch mechanism whereby selected combinations of a plurality of switches may be concurrently operated in a definite sequence by individual control levers, despite the location of the respective switches at different distances from the fulcrum of the control levers.

A further object is to provide a chord selecting button keyboard and switch mechanism having a plurality of closely spaced thin sheet metal button operated levers, normally'biased to nonoperating positions by a plurality of echeloned springs.

A further object is to providea chord selecting button keyboard and switch mechanism having a plurality of button operated levers and a plurality of buttons passing through a supporting plate but free from the levers, in

3 order to eliminate binding from slight misalignments of the parts.

A further object is to provide a chord selecting key button mechanism of the accordion type which is simple, easily manufactured, durable, and inexpensive.

A further object is to provide a depressible bar and switch assembly which is simple, inexpensive, readily demountable as a compact unit, and in which the bar conceals most of the working parts.

Further objects, advantages, and principles of this invention will be apparent from the following description of an illustrative embodiment of the invention, taken with reference to the drawings in which:

Figure 1 is a plan view of a chord selecting button keyboard including a chord envelope controlling bar;

Figure 2 is a side elevational sectional view, taken on the line 2--2 of Fig. 1, of the button keyboard and chord selecting switch mechanism;

Figure 3 is a front sectional view, taken on the line 3-3 of Fig. 1, of the button keyboard and switch mechanism;

Figure 4 is a detail front sectional view, taken on the line 4-4 of Fig. 1, of the chord envelope control bar;

Figure 5 is a detail side sectional view taken on the line 5-5 of Fig. 4 of the accordion chord bar;

Figure 6 is a top sectional view of the chord selecting switch mechanism, taken on the line 66 of Fig. 2;

Figure 7 is a fragmentary front sectional view taken on the line 77 of Fig. 2;

Figure 8 is a fragmentary side elevational sectional view taken on the line 88 of Fig. 3;

Figure 9 is a fragmentary bottom sectional view taken on the line 99 of Fig. 3;

Figure 10 is a fragmentary side sectional view taken on the line 10-10 of Fig. 3;

Figure 11 is .a fragmentary top sectional view taken on the line 11-11 of Fig. 3; and

Figure 12 is a fragmentary sectional view taken on the line 12-12 of Fig. 4.

The keyboard, shown in plan view in Fig. 1, comprises a molded plastic keyboard plate 10 having ninety-six openings 12 formed therein as guides for key buttons 14, the latter being arranged in eight generally horizontal rows and twelve vertical rows, preferably differently colored as indicated by the stippling. The horizontal rows are marked at their left-hand ends with chord designations comprising Major 6th, Ninth, Major, Minor, Seventh, Diminished, Augmented,

and Minor 7th, at their right-hand ends, and with abbreviations of these chord designations such as 6, 9, m, 7, and The chord key designations are marked adjacent the rearward ends of the vertical rows, by the legend, Db, Ab, Eb, Bb, F, C, G, D, A, E, B and Fit, generally as indicated in Fig. 1. For convenience, flatted notes are herein written as the note followed by the letter b as in the preceding sentence. For quick visual identification, certain rows of buttons, such as the vertical rows Eb, C, A, and Fit, are distinctively colored, as indicated by stippling the other buttons 14.

As best shown in Figs. 2 and 3, the keyboard plate 10 has reinforcing pillars or bosses 16 around the openings 12 so as to provide ample guiding surfaces for vertical sliding movement of the key buttons 14. The low bosses 18 around the openings 12 on the upper side of the plate 10 tend to prevent dust and dirt from falling through the clearance spaces between the buttons and the walls of these holes. The key buttons 14 have enlarged heads 20 at their lower ends which rest upon upwardly projecting lugs 22 forming parts of switch selecting levers 24, of which there is one for each key button 14. These selecting levers 24 are pivoted on a rod 26 suitably mounted in a keyboard frame 30 which comprises a number of channels, angles and plates forming a rigid supporting structure for the operating parts, and has the keyboard plate 10 secured thereto by screws 32. Each of the levers 24 is normally swung counterclockwise by a compression coil spring 34 against an upper felt limit stop 36. The springs 34 are arranged in echelon since they are of greater diameter than the spacing of selecting levers 24. The downward or clockwise swinging movement of the levers 24 is limited by a felt downstop 40, these stops 36, being supported by a channel 42 forming part of the frame 30. The levers 24 are stamped of thin sheet metal and are provided with a number of stamped dimples 44 which serve to space them from one another and thus to prevent them from adhering to one another due to the accidental presence of oil.

The lower edges of the levers 24 are provided with a number of projections 46 which are adapted to depress switch actuators 50. There are, of course, ninety-six levers 24, that is, one for each of the 96 key buttons 14, but there are only twenty-four actuators 50. As best shown in Fig. 2, these actuators 50 are in the form of sheet metal levers pivoted on a rod 52 carried in the frame 30 and normally urged clockwise (Fig. 2), each by a separate compression coil spring 54. Alternate actuators 50 have discs 58 made of an insulating material suitably riveted thereto while the intermediate actuators have similar discs 60 of insulating material riveted thereto closer to the pivot rod 52 than the discs 58. The insulating discs or washers, 58, 60 secured to the six leftmost (Fig. 3) actuators preferably are sufliciently larger than the others to make certain that the switches operated by these six actuators will close first and open last as buttons 14 are depressed and released.

To reduce noise, the upper edges of the actuators 50, where they may be engaged by projections 46 of the levers 24, are protected by inverted U-shaped felt pads 62 which are secured to the actuators by staples 64, the latter projecting through suitable openings adjacent the upper edges of the actuators 50.

The insulated discs 60 are arranged to engage and operate a rearward row of switch contactors 66, 68, and (see Fig. 6) while the insulating discs 58 are similarly adapted to engage and operate the forward row of switch contactors 66, 68, and 72. These switch contactors are in the form of thin flexible resilient switch arms having contact wires 74 welded to the lower surfaces of their free extremities. The switch arms 66 are adapted to make contact with the bus bars 76 which are joined by a conducting jumper 77, and the switch contactors 68 are adapted to make contact with bus bars 78 joined by a conducting jumper 79. Similarly the switch contactors 70 are arranged to make contact with a bus bar 80 and switches 72 make contact with the bus bar 82.

The bus bars 76, 78, 80, and 82 are preferably staked to an insulating plate 84 (Fig. 3) and have solder lugs 86 projecting through the plate 84 for attachments of connecting wires. The plate 84 is mounted for longitudinal sliding movement in vertical plates 88 which form part of the frame 30. A metal plate 90 is likewise mounted for longitudinal sliding movement in the vertical frame plates 88. The insulating plate 84 has three holes 92 (Fig. 6) which receive studs 94 riveted to the metal plate 90, and the metal plate 90 is provided with a manually engageable knob 96 by which the plates 84 and 90 may be moved longitudinally. This longitudinal movement is provided so that the bus bars carried by the plate 84 may be shifted relative to the contactors which engage them to present fresh surfaces to the contact wires 74 on these contactors and thereby assure completion of the circuits by the contactors in spite of the presence of dust or other foreign particles which might be present accidentally, even though the switch mechanism is suitably enclosed to prevent admission of dust.

The arrangement of the projections 46 on each key lever 24 differs from the arrangement of the projections on all other key levers. Thus depression of each of the key buttons 14 results in operation of a set of contactors 66, 68, 70, 72 diifering from the set operated by any other key button.

Reliable operation of the button keyboard switching mechanism of this invention depends, among other things, upon the accurate alignment of the switch actuators 50 with the projections 46 on the button levers 24. To insure proper positioning of the actuators 50, a sheet metal guiding plate 110 (Fig. 7) having a plurality of vertical slots 111 is secured to a front channel member 112 of the frame 30 of the switching mechanism. The actuators 50 are slidably positioned in individual slots 111.

The front ends of the actuators 50 protrude through the slotted plate 110 for engagement with a downstop pad 113 which may be secured to a bracket 114 formed by bending the slotted plate 110 outwardly. The downstop pad 113 preferably is inclined downward to the right, as viewed from the front. Thus, the downstop pad 113 slants downward away from the pivot rod 26 (Fig. 3) of the button levers 24, to permit the actuators 50 farther from the pivot rod 26 to be depressed a greater distance than the actuators nearer the pivot rod. All of the particular actuators 50 operated by a given button lever 24 thereby move into engagement with the downstop pad 113 simultaneously.

As best shown in Fig. 8, a pair of combs or plates 116, for guiding the button levers 24, extend transversely above and below the button levers near the pivot rod 26. The combs 116 are suitably secured to the frame 30 of the button switching mechanism. The combs 116 have a plurality of teeth 118 which protrude between alternate button levers 24. One of the combs 116 is positioned to mesh with the upper edges of the button levers 24 and the other comb is positioned to mesh with the lower edges. The teeth 118 extend into notches 120, best shown in Fig. 3, formed in alternate button levers 24 which are aligned with the teeth 118. Thus the spacing of the teeth 118 may be twice the spacing of the button levers 24.

As best shown in Figs. 2, 8, l0, and 11 the button levers 24 are divided into a plurality of groups in bins formed by a plurality of vertical plates 122 suitably secured to the frame 30.

As best shown in Fig. 11, and also in Fig. 3, the ends of the button levers remote from the button lever pivot rod 26 are spaced by a comb or plate 124 suitably secured to the back-to-front channel bracket 42 which also supports the button lever upstop pad 36 and downstop pad 40. The comb 124 has a plurality of fingers 126 bent inwardly in the manner of a rake to mesh with the button levers 24. The fingers 126 are generally aligned with alternate button levers 24 provided with notches 127 in their ends to receive the teeth. The other button levers 24 not provided with notches 127 are thereby efiectively spaced by the fingers 126. The spacing of the fingers 126 may be twice the spacing of the button levers 24.

The combs 116 and 124 and the longitudinal verticalplates 122 provide lateral support for the button levers 24 and substantially reduce or eliminate buckling of the button levers when they are depressed against the downstop pad 40. Because of the lateral support provided by the combs 116 and. 124 and the vertical plates 122 the button levers may be formed from relatively thin sheet metal to secure compactness, light weight, and economy.

Together with the dimples 44, the spacing combs 116 and 124 tend to prevent adjacent button levers 24 from adhering to one another. Independent operation of the button levers 24 is thereby greatly facilitated. Moreover, lighter return springs 34 may be employed for easier operation of the buttons 14.

The arrangement of the button lever return springs 34 is best shown in Fig. 9. As previously mentioned, the diameter of the return springs 34 is considerably greater than the spacing of the button levers 24 and the springs are arranged in multiple echelon formation to prevent interference among adjacent springs.

As best shown in Fig. 10 the button lever upstop pad 36 is horizontal and parallel the button lever pivot rod 26 so that the top edges of the button levers 24 are in a common horizontal plane. Likewise, the top surfaces of the buttons 14 are in another horizontal plane. Consequently, all of the projections 22 extending upwardly from the button levers 24 to engage the buttons 14 may have the same length, and all of the buttons 14 may be of identical construction except for the difference in coloring mentioned previously.

In a view such as Fig. 10 directed toward the button lever pivot rod 26 the button lever downstop pad 40 is seen as slanting downward to the left away from the actuator pivot rod 52 (Fig. 2). Thus button levers 24 farther from the actuator pivot rod 52 may be depressed a greater distance than button levers nearer the actuator pivot rod. Consequently, all of the projections 46, extending from the lower sides of the button levers 24, may have the same length and all of the button levers 24 having projections 46 aligned with a given actuator 50 will be etfective, when operated, to depress the actuator the same distance.

If desired a plate 130 forming part of the frame 30 and positioned adjacent the rear button lever 24 may be provided with slots similar to the slots in the plate 110, for guiding the actuators 50, generally as shown in Fig. 2. Because of the guiding and lateral support provided by the slotted plates and the actuators 50 may be formed from relatively thin sheet metal in the interest of economy and compactness. As previously mentioned, the slotted plates 110 and 130 provide positive alignment of the actuators 50 with the projections 46 extending downwardly from the button levers 24.

The button levers 24 are coded by means of a plurality of notches 132 in order to facilitate assembly of the switching mechanism. A different combination of notches 13.2 is assigned to each of the groups of button levers 24 in the bins provided by the vertical plates 122. The notches 132 indicate at a glance whether all of the button levers 24 are assembled in the proper bins between the plates 122. Moreover, the regularity of the echelon pattern of the return springs 34 indicates whether the button levers 24 are assembled in the bins in their proper order.

To facilitate a players locating the various buttons 14 and to enable the player to depress the proper buttons by touch, a pair of fence-like finger guides is provided, comprising two rods and 141 (Figs. 1, 2, and 3), each supported by four posts 142 and 143 secured in the keyboard plate 10. The posts 142 at the ends of the rods 140 and 141 have sockets to receive the ends of the rods while the intermediate posts 143 have openings through which the rods pass.

The level of the tops of the rods 140, 141 is adjacent and preferably slightly below the plane of the tops of the buttons 14 so that the rods may readily guide the fingers of a player without substantially obstructing the finger motions required for depression of the buttons 14.

The rods 140, 141 form boundaries clearly defining the positions of a plurality of rows of buttons between the rods. The rows of buttons 14 bounded by the finger guiding rods 140, 141, preferably are the rows for the major, minor, and 7th chords, because these three chords occur most frequently in the usual popular and homophonic music. After a little practice, the player soon instinctively associates the location of the rows of buttons for the various chords with their distance from the fencelike finger guiding rods 140, 141. For example, the player soon learns that the row of buttons for the 9th chord is just behind the rear rod 140 and the row of buttons for the diminished chord is just in front of the front rod 141. Having a reference guide dividing the rows of buttons into groups greatly simplifies the playing of an instrument provided with a button board.

The posts 142, 143 project somewhat above the level of the rods and may readily be felt by the fingers of the player. The posts are positioned at regular intervals between various rows of buttons 14 running from back to front. They may be positioned, as illustrated between the Ab and Eb rows, the F and C rows, the D and A rows and the B and F3 rows. Thus three groups, each of nine buttons, are located within the guide formed by the rods and posts. The posts 142, 143 serve to divide the buttons 14 into a plurflity of groups of back-to-front rows or files corresponding with various key signatures. The player soon knows that chords in the key of C must be played in the row of buttons just to the right of the second pair of posts 143 from the left-hand side of the keyboard, for example.

Of course, only a single fence-like guide may be used if desired, or any desired number of guides, running either from left to right or from front to back as desired. However, the particular arrangement of the guide rods or rails 140, 141, described above and illustrated in the drawings, is preferred for its simplicity and practicability.

If desired, the button keyboard may be modified so that the finger guide comprises a plurality of ridges formed integrally with the keyboard plate 10. The tops of the ridges may be provided with irregularities perceptible to the sense of touch to perform the functions of the protruding tops of the posts 142, 143.

If desired, the finger guide may be modified to comprise sheet metal ridges secured to the top of the keyboard plate 10.

A chord intensity envelope control bar 150 which is located directly in front of the button keyboard 10 (Fig. l) is preferably made of a hollow inverted box-like plastic molding having suitable internal reinforcing webs 152 to 158, as best shown in Figs. 4 and 5. This bar is mounted upon an angle-shaped bracket 160 secured to the button keyboard frame 30 and having upwardly extending arms 162 and 163 surrounded by felt strips 164 and 165 cleated thereto forming the primary guides for the sliding movement of the chord bar 1507 The bar 150 is resiliently held in its uppermost position by a pair of coil springs 166 compressed between the bar and the bracket 160. Upward movement of the bar 150 is limited by a pair of felt upstops 168, 169 which are suitably secured to the bracket 160 and which are engaged by small angle brackets 170 secured to the bar 150 by screws 172. Felt downstops 174 and 176 are cemented or otherwise suitably secured within the chord bar 150 near the ends thereof and are adapted to engage upwardly extending end portions 1'78 and 179 of the bracket 160. Ex-

cessive longitudinal sliding movement of the bar 150 is prevented by engagement of the transverse webs or ribs 152, 154, 156, and 158 with the felt pads 164 and 165 and a U-shaped felt pad 180 secured between a pair of upwardly extending arms 182 and 164 of the bracket 160.

A wire 186 is hooked into a bushing 188 positioned in a suitable opening formed in a small spring plate 190 which is frictionally retained inside the chord bar 150, as most clearly shown in Fig. 12. The ends of the plate 190 are positioned in slots 192 formed in a pair of ribs 194. The middle portion of the plate 190 is flexed around a pair of ridges 196 projecting from the rear wall of the chord bar 150, to hold the bushing 188 in engagement with the ridges 196.

The Wire 18-6 extends downwardly through a suitable opening in the lower flange 198 of bracket 160. The lower end of the wire 186 has a rearwardly bent portion 200 (Fig. which lies beneath the end of a flexible resilient switch arm 202, having a contact wire 204, and normally holds the latter from making contact with a fixed contact 296. The switch arm 202 and the fixed contact 206 are mounted on an insulating strip 208 and are suitably insulated from each other and secured by a suitable bracket 210 to the horizontal flange 198 of the bracket 160.

The chord bar 150 may be struck at the middle or at either end and nevertheless cause depression of the central portion thereof sufiiciently to permit the switch arm 202 to make contact with the fixed switch contact 206. Closure of the switch 202, 206 is produced whenever the central portion of the bar is depressed half way, or more. For example, if the right-hand end of the chord bar 150 is depressed, the springs 166 are compressed and the bar pivots around the left-hand upstop 168 so that the central portion of the accordion bar is moved downwardly a sufiicient distance to close the switch 204, 206. Thus the musician need not operate the chord bar with any degree of carefulness since the switch 204, 206 will be closed irrespective of which portion of the chord bar the player presses downwardly.

It will be recalled that the switch contacts 66 may be employed to tune a plurality of electron discharge oscillators and it is highly desirable, in order to avoid undesirable transients, that the tuning be effected prior to the time that connections are made by contacts 68, 70 or 72 to supply electrical tone signals from the oscillators to an output circuit. This is accomplished not only by positioning the contact 66 close to the pivot rod 52, but also by providing larger insulating washers 58, on the switch actuators 50 associated with the switch contacts 66.

It is particularly advantageous that the buttons 14 are not fastened to the selecting levers 24, because the buttons are free to slide up and down in the keyboard plate 10 without any tendency to bind in the plate. There is no possibility of misalignment between the buttons 14 and the openings 12 in the keyboard plate 10.

The switch contacts 66, 68, and 72 may be utilized to perform any desired control functions in musical instruments having electrical control circuits. For example, the contacts may be connected for operating solenoids, controlling pipes reeds, chimes, and other mechanical tone sources.

However, the switch mechanism of this invention is most advantageously employed to control generators of electrical tone signals in an electrical musical instrument. The switch contacts 66, 68, 70 and 72 may be utilized to perform any desired control functions in electrical musical instruments. For example, they may be employed selectively to complete tone signal transmission circuits, to supply energizing electrical power to electrical generators, to operate electromagnetic or electronic relays, or to tune electron discharge oscillators.

As previously mentioned, however, the particular embodiment of this invention illustrated in detail herein is especially adapted to be employed in cooperation with the electrical musical instruments disclosed and claimed in the previously mentioned Hanert patent. The six switch contacts 66 may be employed for tuning the six tunable oscillators of one of the embodiments described in this Hanert application. The six switch contacts 68 may be employed selectively to connect the six oscillators respectively with a common output system. The six contacts 70 may be utilized selectively to connect the oscillators with a root output conductor, and the contacts 72 may be employed to connect the oscillators with a fifth output conductor. The embodiment described in the Hanert application has a manual control for connecting either the root or the fifth output conductor with the output system through a unitary frequency dividing sysem for lowering the pitch of the root or the fifth input signal by a plurality of octaves to provide low pitched sub-bass tones.

The operation of the keyboard and switching mechanism has already been described but will now be summarized briefly.

The player locates a desired control button 14 with the aid of the finger guiding rods and 141 and posts 142 and 143. He depresses the button 14 as far as it will go. The particular button lever 24 engaging 9 the depressed button 14 is rotated clockwise (Fig. 3) on the pivot rod until the button lever engages the downstop pad 40.

An individual combination of switch actuators 50 is thereby depressed by the projections 46 on the depressed button lever 24. As clearly shown in Fig. 3, the actuators farther from the button lever pivot rod 26 are depressed a greater distance than those nearer the pivot rod. As shown in Fig. 7 the actuator downstop pad 113 is inclined to permit greater depression of the actuators farther from the pivot rod.

As shown in Fig. 2, the washers 58 and 60 flex the contact springs downwardly until the ends of the contacts engage the bus bars 80 and 82, and further downward motion of the washers 58 and 60 bows the central portions of the switch contacts downwardly.

Operation of the switch contacts, by performing various control functions such as tuning and keying, is effective to sound a complete musical chord comprising at least three harmonically related musical tones.

The chord bar 150 may be struck to change the intensity of the chord selected by depression of a control button 14. Depression of the chord bar 150 closes the switch 204, 206 which may be connected, for example, to energize an electron discharge intensity envelope control tube, as more fully described and illustrated in the Hanert application Serial No. 169,891, previously mentioned.

When the depressed control button 14 is released, the biasing spring 34 returns the button lever 24 into engagement with the upstop pad 36, and the button 14 resting on the lever 24 is also returned to its normal position. The actuators 50 are returned by their biasing springs 54 so that contact is maintained between the projections 46 on the button lever 24 and the felt pads 62 secured to the tops of the actuators 50.

While I have shown and described a particular embodiment of my invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereof, without departing from the more fundamental principles of the invention. I therefore desire, by the following claims, to include within the scope of my invention all such similar and modified forms of the apparatus disclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

I claim:

1. In a button chord keyboard and switch mechanism for an electrical musical instrument, the combination of a plurality of switches respectively having individual flexible contact members, a plurality of parallel switch actuators positioned adjacent the flexible contact members respectively, a plurality of parallel button levers extending across the switch actuators and respectively having combinations of projections of substantially equal length extending toward predetermined switch actuators, a plurality of relatively short electrically insulating lugs secured to predetermined individual switch actuators constituting a first group and extending toward the fiexible contact members, and a plurality of relatively long insulating lugs secured to other individual switch actuators constituting a second group, whereby a switch positioned adjacent an actuator of the first group is operated an interval after a switch positioned adjacent a lever of the second group when a key button lever having projections for operating both of said switches is depressed.

2. In a button keyboard and switch mechanism of an electrical musical instrument, the combination of a plurality of parallel generally horizontal switch levers, a switch lever pivot rod rotatably supporting each of the switch levers at one end, a plurality of parallel generally horizontal button levers adjacent and transverse to the switch levers, a button lever pivot rod rotatably support ing each of the button levers at one end, an upstop parallel with the button lever pivot rod positioned adjacent the upper sides of the button levers remote from the button lever pivot rod, 2. downstop positioned adjacent the lower sides of the button levers remote from the button lever pivot rod and slanting downwardly away from the switch lever pivot rod, a switch lever downstop positioned adjacent the lower side of the ends of the switch levers remote from the switch lever pivot rod upon depression of the switch levers and slanting downwardly away from the button lever pivot rod, and a plurality of projections respectively extending downwardly from each of the button levers toward predetermined switch levers in selected combinations.

3. For use in an electrical musical instrument the combination of a button keyboard of the accordion type comprising a horizontal bass plate and key buttons guided for vertical reciprocation in the plate, an elongated accent control bar located in front of the button keyboard and extending substantially the full length of the latter whereby it may be operated by the hand or wrist of the player while a finger of the hand is holding one of the key buttons depressed, means secured to the bass plate to guide the bar for vertical movement, a pair of upstops engageable with the bar adjacent its ends respectively, means including a spring biasing the bar against the upstops, means providing a downstop positioned for engagement with the bar upon depression thereof, and a switch operator connected with the bar near its center and operable by depression of the entire bar half way between the upstops and downstop, whereby full depression of either end of the bar effects operation of the switch.

4. For use in an electrical musical instrument the combination of a button keyboard of the accordion type comprising a horizontal bass plate and key buttons guided for vertical reciprocation in the plate, an elongated accent control bar having a downwardly opening cavity, said bar being located in front of the button keyboard and extending substantially the full length of the latter whereby it may 'be operated by the hand or Wrist of the player while a finger of the hand is holding one of the key buttons depressed, a bracket removably secured to the bass plate and extending into the cavity in the control bar to guide the bar for vertical movement, a pair of upstops on the bracket engageable with the bar adjacent its ends respectively, means including a spring connected between the bar and the bracket and biasing the bar against the upstops, means providing a downstop positioned for engagement with the bar upon depression thereof, a switch secured to the bracket, and a switch operator connecting the bar with the switch, whereby the bar, switch, and bracket maybe removed from the bass plate as a compact unit.

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